Studies of frequency-tripled ND:YAG laser in laser structuring process

As demand for a higher densities and more flexible technology in the fabrication of finer lines/spaces on PCB boards, a new technology –laser structuring – has emerged in recent years. In this work, the frequency-tripled Nd:YAG laser is selected as the laser source in laser structuring. This laser is often used in miniaturization machining. This work discusses the feasibility of laser structuring as a new method in PCB fine lines/spaces fabrication. The essential processes in laser structuring such as tin electroplating process, laser direct structuring process and etching process are discussed here. Some important parameters are studied in detail to find out their effects on the laser structuring results including the electroplating parameters-- electroplating time and uniformity of tin layer, the laser parameters—laser power, numbers of repetitions, repetition rate and bite size, the etching parameters—etching time and the cross section profile of spaces, and so on. The smallest width of fine line achievable by laser structuring with frequency tripled Nd:YAG laser is also studied in this work. The width of fine line is influenced not only by laser parameters, but also by etching process.